libstagefright: Reset buffer size value with SurfaceTexture

- OMXCodec explicitly sets the decoder output buffer size using the
  native window perform API. (to accomodate extra-data)
- This size is reset only when the SurfaceTexture is destroyed.
- Unless reset, this size will be assumed for all output buffers
  if the SurfaceTexture is re-used.
CRs-Fixed: 337660, 432309

Change-Id: I28aed12ad02adeac61caffbb00e3082640a5f6d4